.... I agree with Bill. A lot has been said about the zddp/zinc in oil. If my memory serves me correctly this all started over some cam failures.
The MAIN concern here is on startup/break-in of an engine. The break-in or the first 20-30 minutes of engine run time will decide if the cam fails due to lack of zddp or not. I always put a quart of EOS (Engine Oil Supplement) from the Chevy dealer in my engines. They stopped carrying it for a while but I hear they have it again? After that I never use it anymore and just make sure I change my oil on a timely basic.
The "action/marriage/hardening" or what ever the proper name is, for the cam/lifter metal conditioning happens in the first few minutes and then its over!
About 2 or 3 years ago, while delivering parts to garage "David" told me about engine failure on a Chevy engine he built and that it was the oil...he never added any supplement, that caused the cam/lifter failure. I looked at the actual lifters and they were eat out on the bottom pretty bad in what amounted to maybe 100 miles. David then showed me letters he received from cam companies who responded to his concerns. The articles spoke of many failed cam/lifter sets due to the lack of ZDDP. Well, David used the same stuff again, put in a quart of EOS,ran the engine in and never had any problem. Lesson learned.
It was also a lesson for me. Even though I always used the EOS I had not heard at the time about the elimination of ZDDP. It does pay to stay abreast of what is going on.... .which the Stovebolt does a good job of at least getting it on the front page!!
This is first hand info.... what the other details involved I don't know but its all in the break in that we should "mainly" be concerned. Thats when the damage is done. In my opinion it really don't matter on existing running engines except for maybe on the really old stuff and I can't properly addrsss them.
